มีปัญหาเรื่อง CheckBox ใน DataGridView คะ มีปัญหาเรื่อง CheckBox ใน DataGridView คะ ใช้ vb2005

namespace Global
{
    public static class GlobalValue
    {
        private static  DataTable dtb = null;

        public static  DataTable Dtb
        {
            set { dtb = value; }
            get { return dtb; }
                    
        }
     
    }
}

Private sub Refresh_Grid()
        Dim d_adap As SqlDataAdapter
        Dim d_set As DataSet
        d_set = New DataSet

        d_adap = New SqlDataAdapter("Select Dog_ID,Register_No,Dog_Name,Dog_Sex,Dog_Color,Dog_Price " & _
                                    " from Kennel_Dog Where Dog_Status = 'SA' ", sqlConnection)

        d_adap.Fill(d_set, "Kennel_Dog")
        DataGridView.DataSource = d_set.Tables("Kennel_Dog")

        Dim chkColumn As New DataGridViewCheckBoxColumn()
        chkColumn.Name = "check"
        chkColumn.Width = 30
        chkColumn.DataPropertyName = "check"
        chkColumn.HeaderText = ""
        chkColumn.DisplayIndex = 0
        DataGridView.Columns.Add(chkColumn)

        DataGridView.Columns("Dog_ID").DisplayIndex = 1
        DataGridView.Columns("Register_No").DisplayIndex = 2
        DataGridView.Columns("Dog_Name").DisplayIndex = 3
        DataGridView.Columns("Dog_Sex").DisplayIndex = 4
        DataGridView.Columns("Dog_Color").DisplayIndex = 5
        DataGridView.Columns("Dog_Price").DisplayIndex = 6

        DataGridView.Columns("Dog_ID").HeaderText = "รหัสสุนัข"
        DataGridView.Columns("Register_No").HeaderText = "เลขทะเบียน"
        DataGridView.Columns("Dog_Name").HeaderText = "ชื่อ"
        DataGridView.Columns("Dog_Sex").HeaderText = "เพศ"
        DataGridView.Columns("Dog_Color").HeaderText = "สี"
        DataGridView.Columns("Dog_Price").HeaderText = "ราคา"

        DataGridView.Columns("Dog_ID").Width = 70
        DataGridView.Columns("Register_No").Width = 100
        DataGridView.Columns("Dog_Name").Width = 140
        DataGridView.Columns("Dog_Sex").Width = 40
        DataGridView.Columns("Dog_Color").Width = 100
        DataGridView.Columns("Dog_Price").Width = 90

        AddHandler DataGridView.CellContentClick, AddressOf DataGridView_CellContentClick
End sub

 Private Sub Form13_1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Refresh_Grid()
    End Sub

    Private Sub DataGridView_CellContentClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView.CellContentClick

        Dim chk As DataGridViewCheckBoxCell = DirectCast(DataGridView.CurrentCell, DataGridViewCheckBoxCell)
        'If chk.Value Is Nothing Then
        '    Exit Sub
        'End If
        If CInt(chk.Value) = 0 Then
            chk.Value = 1
            'MessageBox.Show(("คุณเลือก : " & DataGridView.CurrentRow.Cells("Dog_ID").Value.ToString()))
        Else
            chk.Value = 0
        End If
    End Sub